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#### 1 MariaDB主从复制原理
主数据库更新数据，生成二进制日志写入到binlog中,启动dumpthread 线程(salve服务线程)，

从数据库开启IOthread线程读取主数据库binlog日志，写入到中继日志(relay log)中并启动SQL thread 读取日志，更新数据到从数据库中。实现主从数据一致。

#### 2 MariaDB一主一从架构构建

准备两台纯新的CentOS7.6服务器，其中主机称为node1的服务器地址为192.168.130.132，主机称为node2的服务器地址为192.168.130.133
主节点node1 192.168.130.132 配置文件

[mysqld]

log_bin

server-id=132

#修改数据库配置文件需要重启数据库

systemctl restart mariadb 

主服务器主节点node1 192.168.130.132 创建可以复制权限的账号及密码

GRANT REPLICATION SLAVE ON *.* TO repl@'192.168.130.%' IDENTIFIED BY 'replpass';

show master statusG #查询当前主库日志文件及位置

File: maridb-bin.000004
Position: 154
Binlog_Do_DB:
Binlog_Ignore_DB:
Executed_Gtid_Set:
1 row in set (0.00 sec)

从节点node2 192.168.130.133 配置文件

[mysqld]

log_bin

server-id=133

read_only=on #默认会开启

relay_log=relay-log

relay_log_index=relay-log.index

#修改数据库配置文件需要重启数据库

systemctl restart mariadb 

#从节点使用有权限的账号及密码连接主库，通过日志文件及位置，开启同步。直至合主库数据一致

CHANGE MASTER TO MASTER_HOST='192.168.130.132',

MASTER_USER='repl',

MASTER_PASSWORD='replpass',

MASTER_LOG_FILE='maridb-bin.000004',

MASTER_LOG_POS='154';

start slave;

show slave statusG

(注意 yes ,yes 代表同步开启)

#### 3 MariaDB级联复制

上一节中我们完成了一主一从的MariaDB的主从复制架构，但是有的时候，我们期望有一个后备的MariaDB的节点，用只
动词}备份存储数据，不需要对外提供服务。为了实现该功能，我们可以在之前的一主一从架构上进行调整，即将从节点的二进
制文件打开，然后给他配置一个远程同步数据用户，接着使用一台新的服务器做为从服务器的从属，同步从服务器数据的即
柯林斯，下面我们在原来的架构上添加一台新的CentOS7.6，作为节点3，IP地址为192.168.132.134

 

#主从同步一致的情况下

#中间节点 node2 192.168.130.133 配置文件

[mysqld]

log_bin

server-id=133

read_only=on #默认会开启

log_slave_updates

#修改数据库配置文件需要重启数据库

systemctl restart mariadb 　　

#中间节点服务器全库备份库

mysqldump -A -F --single-transaction --master-data=2 >/back/all.sql

scp /back/all.sql root@192.168.130134:/root/

#node3 192.168.130.134 配置文件

[mysqld]

log_bin

server-id=134

read_only=on

#修改数据库配置文件需要重启数据库

systemctl restart mariadb 

vim /back/all.sql

CHANGE MASTER TO MASTER_HOST='192.168.130.133',

MASTER_USER='repl',

MASTER_PASSWORD='replpass',

MASTER_LOG_FILE='maridb-bin.000004',

MASTER_LOG_POS='154';

source /back/all.sql;

show master logs;

start slave statusG

#### 4 MariaDB半同步复制

主节点半同步设置
[mysqld]

server-id=132

log-bin

plugin_load_add=semisync_master

rpl_semi_sync_master_enabled=on

rpl_semi_sync_master_timeout = 20000

#修改数据库配置文件需要重启数据库

systemctl restart mariadb 

注意官方提供安装插件不用修改配置文件重启库

主节点半同步变量查看

show GLOBAL VARIABLES LIKE '%semi%';

主节点半同步状态查看
show GLOBAL STATUS LIKE ‘%semi%’;

从节点配置

[mysqld]

server-id=133

plugin_load_add = semisync_slave

rpl_semi_sync_slave_enabled=on

从节点半同步变量查看

show GLOBAL VARIABLES LIKE '%semi%';

从节点半同步状态查看
show GLOBAL STATUS LIKE ‘%semi%’;

#### 5 MariaDB高可用方案MHA

准备三台新安装的CentOS7.6服务器，并使用yum安装MariaDB10.2.23，主机名分别为node1，node2，node3，
IP地址分别为192.168.130.132-134

1 ssh 验证省略 （实现三台机器互联）

2 安装  mha

三个节点服务器分别安装 yum -y install  mariadb-server

192.168.130.132  master 主节点安装

yum -y install  mha4mysql-manger-0.56-0.el6.noarch.rpm

yum -y install mha4mysql-manger-0.56-0.el6.noarch.rpm

192.168.130.133 ，192.168.130.134 slave 从节点安装

yum -y install mha4mysql-manger-0.56-0.el6.noarch.rpm

3 修改 192.168.130.132 master配置及mha　manger 配置文件

[mysqld]

server_id=132

log-bin

skip_name_resolve=1 #禁止反向解析

general_log

systemctl restart mariadb

创建复制的主的从账号

grant replication slave on *.*　to  repl@'192.168.130.%' identified by 'replpass'

创建可以切换的主账号

grant all on　* .*  to  mhauser@'192.168.130.%' identified by 'mhapass'

vip 配置供外部访问，主库崩溃可以飘到其他机器上的IP

ifconfig eht0:1　192.168.130.100/24

mkdir //etc/mastermha/

vim /etc/mastermha/app.cnf

[server default]

user=mhauser

password=mhapass

manger_workdir=/data/mastermha/app/

manger_log=/data/mastermha/app/

remote_workdir=/data/mastermha/app/

ssh_user=root

repl_user=repl

repl_password=replpass

ping_interval=1

master_ip_failover_script=/usr/local/bin/master_ip_failover

report_script=/usr/local/bin/sendmail.sh

check_repl_delay=0

[server1]

hostname=192.168.130.133

[server2]

hostname=192.168.130.134

cat master_ip_failover

#!/usr/bin/env perl
use strict;
use warnings FATAL => 'all';
use Getopt::Long;
my (
$command, $ssh_user, $orig_master_host, $orig_master_ip,
$orig_master_port, $new_master_host, $new_master_ip, $new_master_port
);
my $vip = '192.168.130.100';#设置Virtual IP
my $gateway = '192.168.130.254';#网关Gateway IP
my $interface = 'eth0';
my $key = "1";
my $ssh_start_vip = "/sbin/ifconfig $interface:$key $vip;/sbin/arping -I $interface -c 3 -s $vip $gateway >/dev/null 2>&1";
my $ssh_stop_vip = "/sbin/ifconfig $interface:$key down";
GetOptions(
'command=s' => $command,
'ssh_user=s' => $ssh_user,
'orig_master_host=s' => $orig_master_host,
'orig_master_ip=s' => $orig_master_ip,
'orig_master_port=i' => $orig_master_port,
'new_master_host=s' => $new_master_host,
'new_master_ip=s' => $new_master_ip,
'new_master_port=i' => $new_master_port,
);
exit &main();
sub main {
print " IN SCRIPT TEST====$ssh_stop_vip==$ssh_start_vip=== ";
if ( $command eq "stop" || $command eq "stopssh" ) {
# $orig_master_host, $orig_master_ip, $orig_master_port are passed.
# If you manage master ip address at global catalog database,
# invalidate orig_master_ip here.
my $exit_code = 1;
eval {
print "Disabling the VIP on old master: $orig_master_host ";
&stop_vip();
$exit_code = 0;
};
if ($@) {
warn "Got Error: $@ ";
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "start" ) {
# all arguments are passed.
# If you manage master ip address at global catalog database,
# activate new_master_ip here.
# You can also grant write access (create user, set read_only=0, etc) here.
my $exit_code = 10;
eval {
print "Enabling the VIP - $vip on the new master - $new_master_host ";
&start_vip();
$exit_code = 0;
};
if ($@) {
warn $@;
exit $exit_code;
}
exit $exit_code;
}
elsif ( $command eq "status" ) {
print "Checking the Status of the script.. OK ";
`ssh $ssh_user@$orig_master_host " $ssh_start_vip "`;
exit 0;
}
else {
&usage();
exit 1;
}
}
# A simple system call that enable the VIP on the new master
sub start_vip() {
`ssh $ssh_user@$new_master_host " $ssh_start_vip "`;
}
# A simple system call that disable the VIP on the old_master
sub stop_vip() {
`ssh $ssh_user@$orig_master_host " $ssh_stop_vip "`;
}
sub usage {
print
"Usage: master_ip_failover --command=start|stop|stopssh|status --orig_master_host=host --orig_master_ip=ip --orig_master_port=port --new_master_host=host --new_master_ip=ip --new_master_port=port ";
}

cat sendmail.sh

#!/bin/bash
echo "MySQL is down" | mail -s "MHA Warning" root@tyzh.com

slave 从节点192.168.130.133,192.168.130.134配置 

[mysqld]

server_id=133(134机器需要修改）

log-bin

skip_name_resolve=1 #禁止反向解析

relay_log_purge=0

read_only

systemctl restart mriadb

CHANGE MASTER TO MASTER_HOST='192.168.130.133',

MASTER_USER='repl',

MASTER_PASSWORD='replpass',

MASTER_LOG_FILE='maridb-bin.000004',

MASTER_LOG_POS='154';

start slave statusG

检查

masterha_check_ssh --conf=/etc/mastermha/app.cnf

masterha_check_repl --conf=/etc/mastermha/app.cnf

启动mha

nohup masterha_manager --conf =/etc/mastermha/app.cnf &>　 /dev/null

masterha_check_status --conf =/etc/mastermha/app.cnf